1. Field of the Invention
The present invention relates to a vibration reduction structure of a reciprocating compressor capable of preventing vibration generated from an assembly composed of a piston, a cylinder, and a driving unit from being transmitted to an entire case at the time of operating the compressor, and more particularly, to a vibration reduction structure of a reciprocating compressor capable of effectively reducing vibration by installing a loop pipe between an assembly and a case and installing an additional connection unit at the loop pipe in order to discharge a compressed refrigerant.
2. Description of the Conventional Art
Generally, a compressor is a device for enhancing a pressure by compressing various gas such as air, refrigerant, etc. by receiving power from a power generating device such as an electric motor, a turbine, etc. The compressor is being widely used in home appliances such as a refrigerator, an air conditioner, etc. or throughout the industry.
The compressor can be classified into a reciprocating compressor for compressing a refrigerant as a piston is linearly reciprocated in a cylinder with forming a compression space for sucking and discharging operation gas between the piston and the cylinder; a rotary compressor for compressing a refrigerant as a roller is eccentrically-rotated along an inner wall of a cylinder with forming a compression space for sucking and discharging operation gas between the eccentrically rotated roller and the cylinder; and a scroll compressor for compressing a refrigerant as an orbiting scroll is rotated along a fixed scroll with forming a compression space for sucking and discharging operation gas between the orbiting scroll and the fixed scroll.
Recently, among the reciprocating compressors, a linear compressor having a simplified structure and capable of enhancing a compression efficiency without a mechanical loss due to a motion conversion by directly connecting a piston to a linearly-reciprocating driving motor is being much developed.
FIG. 1 is a lateral section view showing a reciprocating compressor in accordance with the conventional art.
As shown, the general reciprocating compressor compresses operation fluid such as refrigerant, etc. as a piston is linearly reciprocated in a cylinder. FIG. 1 shows a linear compressor among the reciprocating compressor. The reciprocating compressor comprises: a case 2 to which a suction pipe 30 for introducing a refrigerant and a discharge pipe 31 for discharging a refrigerant are connected; a cylinder 4 installed in the case 2; a piston 6 linearly-reciprocated in the cylinder 4, for sucking a refrigerant into a compression space P, compressing, and then discharging the refrigerant; a driving unit 10 fixed to an outer side of the cylinder 4, for linearly-reciprocating the piston 6; a suction valve 24 installed at one end of the piston 6 that forms the compression space P, for sucking a refrigerant to the compression space P; and a discharge valve assembly 20 installed at one end of the cylinder 4 that forms the compression space P, for discharging a refrigerant from the compression space P to the discharge pipe 31.
The cylinder 4 is formed as a hollow type so that the piston 6 can be linearly-reciprocated therein, and is provided with the discharge valve assembly 20 at one end thereof.
The piston 6 is provided with a refrigerant channel 7 at a center thereof so that a refrigerant introduced from the suction pipe 30 can flow, and is inserted into the cylinder 4 thereby to form a compression space P at one side thereof. Also, one end of the piston 6 is elastically supported by a supporting frame 26 separately installed from the cylinder 4 by restoration springs 8 and 9 installed in an axial direction.
The driving unit 10 is composed of: a cylindrical inner stator 12 fixed to an outer side of the cylinder 4 and formed as a plurality of lamination sheets 11 are laminated in a circumferential direction; a cylindrical outer stator 14 installed at an outer side with a certain interval and formed as a plurality of lamination sheets 17 are laminated on an outer side of a coil 15 in a circumferential direction; and a permanent magnet 16 installed between the inner stator 12 and the outer stator 14 and connected to another end of the piston 6 by a mounting member 18.
The inner stator 12 and the outer stator 14 are fixed to an outer side of the cylinder 4 by a frame 19, and the permanent magnet 16 is installed to be linearly-reciprocated with the mounting member 18 and the piston 6.
The suction valve 24 is formed as a thin plate shape and a center portion thereof is positioned at one end of the piston 6. The center portion of the suction valve 24 is partially cut to open and close the refrigerant channel 7, and one side of the suction valve 24 is fixed to one end of the piston 6 by a screw.
The discharge valve assembly 20 is composed of: a discharge cover 21 installed to form a discharge space O at a side of one end of the cylinder 4; a discharge valve 22 for opening and closing one end of the of the cylinder 4; and a valve spring 23 installed between the discharge cover 21 and the discharge valve 22, for providing an elastic force in an axial direction.
A curved loop pipe 28 is installed between one side of the discharge cover 21 and the discharge pipe 31. The loop pipe 28 guides a compressed refrigerant to be discharged outwardly, and prevents vibration generated by a reciprocal operation among the cylinder 4, the piston 6, and the driving unit 10 from being transmitted to the entire case 2.
FIG. 2 is a perspective view showing the loop pipe of the reciprocating compressor in accordance with the conventional art. When a natural frequency of the loop pipe 28 is equal or similar to an operation frequency of the piston 6, a resonance is occurred. Therefore, in order to prevent the resonance occurrence, the loop pipe 28 is designed to have a natural frequency that is not equal or is not similar to the operation frequency of the piston 6, thereby preventing vibration and noise from being transmitted to the case 2.
The cylinder 4, the piston 6, the driving unit 10, and an oil supplying device 40 are connected to one another thereby to form an assembly. The assembly is installed in the case 2 to be supported by a buffering device such as a supporting spring 29, etc.
The oil supplying device 40 for supplying oil stored at an inner lower side of the case 2 to a space between the piston 6 and the cylinder 4 is installed at a lower side of the frame 19, thereby preventing a friction between the piston 6 and the cylinder 4 and cooling the cylinder 4.
In the conventional vibration reduction structure for the scroll compressor, the loop pipe 28 for guiding a refrigerant to be discharged is installed between the assembly and the discharge pipe 31, and the assembly is supported by a buffering device such as the supporting spring 29, etc. at the lower side of the case 2, thereby reducing vibration.
Since the loop pipe 28 is curvedly formed so that a vibration transmission path can be longer, vibration generated from the assembly is reduced while being transmitted along the loop pipe 28. At this time, the supporting spring 29 reduces vibration generated from the assembly in the up-down direction.
In the conventional vibration reduction structure for the reciprocating compressor, since the loop pipe 28 is curvedly formed to be welded to the discharge cover 21 and the discharge pipe 31, a vibration transmission path becomes long and thereby a vibration transmission to the case 2 is reduced. However, there is a limit in making the loop pipe 28 long. Also, in case that the loop pipe becomes different from the original design condition due to various changes of an operation frequency of the driving unit 10 or various external influences, etc., a resonance is occurred and vibration having a comparatively great displacement is generated at a specific part of the loop pipe. The generated vibration is transmitted to the connection part of the loop pipe and thus the connection part is destroyed, thereby degrading a reliability of the product.